Sand consolidation method



United States Patent 3,221,814 SAND CONSOLIDATION METHOD Wayne F. Hower, Duncan, Okla, assignor to Hallibnrton Company, Duncan, Okla, a corporation of Delaware No Drawing. Filed Apr. 1, 1963, Ser. No. 269,767 4 Claims. (Cl. 166-33) The present invention relates to a new and improved method of consolidating loose or incompetent sands and more particularly to a new and improved method of consolidating a formation traversed by a bore hole.

A variety of methods and techniques have been employed to prevent or inhibit the migration of loose sands with the production of crude oil or gas and water. One of these methods has been the use of a resin or resinous system wherein the unconsolidated or loose sands are wetted with a resin or resin forming material, and such resin or material is treated or cured so as to bond the sand grains of the formation together thereby forming a consolidated permeable formation.

One method of consolidating loose sands with resin or plastic, is disclosed in copending application Serial No. 260,831, filed February 25, 1963. Other methods of consolidating incompetent formations traversed by a bore hole are disclosed in US. Patents Nos. 2,378,817, 2,476,- 015, 2,604,172, 3,022,825, and 3,047,067.

In consolidating incompetent sands in a producing well, it is essential that the consolidation be sufliciently strong or have a compressive strength such that the flow of well fluids therethrough will not cause the consolidation to break down and cause the well to produce sand. It is also essential that the consolidation be stable in the various well fluids and at varying pressures and temperatures.

Insufficient strength of the consolidation to withstand the draw down of well fluids or instability of the consolidation in such fluids results in the well producing sand or sanding up.

It is also essential that the method of carrying out the sand consolidation be sufficiently flexible that it can be readily performed under field conditions, and performed economically. It is preferred that such sand consolidation method also be able to be performed with relative ease and without difliculty.

It is, therefore, an important object of the present invention to provide a new and improved permeable and consolidated barrier adjacent to a Well bore, which barrier is sufficiently strong and stable so as to facilitate fluid production essentially free of solids.

Another important object of the present invention is to substantially increase the compressive strength of permeable resinous sand consolidations.

Still another object of the present invention is to provide a new and improved method of permeably consolidating loose or incompetent sands or formations, which method can be performed relatively easily and economically.

Another object of the present invention is to provide a new and improved method of consolidating loose or incompetent sands with a phenolic plastic or resin.

Other objects and advantages of the present invention will become readily apparent from a reading of the specification and claims hereinbelow.

One particular method of sand consolidation currently being used with some degree of success in the field utilizes five basic steps as follows:

(1) Introducing a formation conditioner into the well formation.

(2) Preflushing the formation with an organosilicon compound.

(3) Following the preflush with a spacer.

(4) Introducing a phenolic plastic or resin into the formation.

3,221,814 Patented Dec. 7, 1965 "ice Formalin 69.16 M-P cresol 13.30 3,5 Xylenol 1.56 Guanidine carbonate 11.87 Caustic soda solution 4.11

(5) Afterflush-A 2.5% cresol in diesel oil solution. One volume of the various fluids used in this illustrated method is as follows:

Barrels (1) Formation conditioner 5 (2) Preflush 5 (3) Spacer 3 (4) Plastic 4 (5) Afterflush 2 It can readily be appreciated that certain variations are made in the volume of the materials as well as the formulas, depending upon the field conditions and the desired results.

Other organosilicon compounds can be used than the one specifically shown.

A paper entitled, Sand Consolidation with Base- Catalyzed Plastic, by H. H. Spain, presented at the Spring meeting of the Southern District Division of Production, American Petroleum Institute in Houston, Texas, on or about March 1, 1962, explains the process in detail, its laboratory development, field tests thereof, its variations with recommended ranges, and the results of the tests.

Although it is believed that the silane preflush has been an important factor in the successful results obtained in the field, there are some distinct disadvantages in the way it has been used.

This prior art method requires that two separate solutions be pumped in order to successfully use the silane preflush. This requires additional tanks, which often complicates well treatments, particularly offshore treatments.

In addition, there is an in situ reaction involved wherein the plastic must contact the silane or organosilicon compound in the formation to obtain the hard or strong consolidation necessary for a successful treatment.

The present invention is an improvement over this prior art base-catalyzed method of consolidating loose or incompetent sands.

The particular silane, N-(betaaminoethyl)-gammaaminopropyltriethoxysilane, used in the prior art preflush and method, reacts rapidly with the plastic, and, there fore, is preferably not added directly to the plastic. Silanes of this type are not considered to be compatible in the plastic because of the rapid formation of a gummy reaction product. Although a plastic made including this type of silane will penetrate some sands reasonably well, a severe permeability reduction of the sand near the perforation is likely, especially where a large volume of plastic is forced through one perforation.

It has been discovered that by mixing a small amount of a silane compatible with the plastic, directly with the plastic, that the preflush and spacer steps of the prior art can be completely eliminated, and that an equal or better sand consolidation can be brought about.

The silane, in order to be compatible with the plastic or consolidating resin, is preferably one which can be added directly to the plastic without changing the separation time or setting characteristics of the plastic. Only half as much of the silane is required when adding the silane directly to the plastic as is required in the preflush to accomplish the same results, and even then the consolidation made with the plastic-silane consolidating fluid is usually a better one.

Gamma-aminopropyltriethoxysilane is an example of the preferred silane which is compatible with the base-catalyzed plastic recommended in the method of this invention.

The addition of this preferred type of silane directly to the plastic eliminates two steps in the placement of the plastic and reduces the number of mixing tanks required for a treatment. It also assures direct contact of the silane and plastic which eliminate the in situ reaction required where a silane of the N-(beta-aminoethyl)-gamma-arninopropyltriethoxysilane type is used in a preflush.

The present invention employs three basic steps as follows:

(1) Introducing a formation conditioner into a well formation which is to be consolidated.

(2) Introducing a phenolic resin or plastic into the formation.

(3) Introducing an overflush or afterfiush solution into the formation.

It can be appreciated, that variations within the scope of the appended claims may be made in the materials used in each step without departing from the scope of the invention.

The formation conditioner is preferably diesel oil with about 0.5 to about 3% of an oil soluble surfactant or surface active agent mixed therewith. Greater amounts of the surfactant may be used if desired, but no appreciable benefits are derived.

The plastic or resin preferably contains from about .05 to about 5% of the silane. Greater amounts may be used if desired, but again, no appreciable benefits are derived.

The afterfiush or overflush solution preferably is a mixture of oil and from about 1% to about 3% cresol. A sufficient amount of cresol should be admixed with the oil to prevent the oil from extracting the cresol-phenol content from the resin solution, and thereby inhibiting the set or curing of the resin. The use of too much cresol in the oil, apparently results in the cresol solubilizing the cresol and/or phenol in the resin, thus inhibiting the set of the resin.

The present invention has a number of distinct advantages over the prior art method described hereinabove. The overall number of treating steps is reduced from five or six to three or even two if an afterflush is omitted. The advantage of this feature is believed to be readily apparent.

The present invention assures that the plastic is in contact with the desirable silane in all instances rather than depending upon an in situ contact. This results in a better and stronger consolidation.

Water is eliminated from the treating sequence. It is generally desirable to avoid pumping water into a producing well formation.

The present invention may be used with the phenolic resin formulas covering the 85 F. to 230 F. range.

The total volume of fluids used in carrying out the present invention has been substantially reduced. The more fluids pumped into a formation, the greater the chances of fracturing and failing to properly consolidate the formation.

A number of laboratory tests were conducted which effectively illustrate comparisons of the present invention with the prior art method.

As the silane, N-(beta-aminoethyl)-gamma-aminopropyltriethoxysilane, reacts rapidly with the plastic or resin used in this invention, it is preferably not added directly This group of laboratory tests included separation time tests, compatibility tests and compressive strength determinations. Three basic plastic formulas for temperatures of 130 F., 146 F., and 178 F. were used. These formulas are designated A, B and C respectively, and are as follows:

A B C Formalin cc 100 cc 100 cc. M-P cresol..- 20 cc. 20 cc. Phenol. 20 cc. 3,5 xylenol 2.43 Guanidine carbonate-. 18.5 gins- 16.7 grns- 17.1 gms. 36% caustic solution... 4.6 cc 4.16 cc- 4.35 cc.

The chemicals used were pre-cooled as necessary.

Separation time tests.-Tests were made using each of the three plastic formulas without the silane added and with 9.37% and 0.74% of gamma-aminopropyltriethoxysilane mixed therewith. No significant change in the separation times were noted.

Compatibility tests.The gamma-aminopropyltriethoxysilane was compatible with each of the three plastic formulas. The silane was added to the plastic just prior to the addition of the 36% caustic soda solution and a cloudy solution was formed. The addition of the caustic soda caused a clear solution to be formed in a short time.

Compressive strength tests-Oklahoma #1 sand was packed 2 /2 inches deep in 1 ,1 inches I.D. glass tubes and treated in accordance with the two methods as follows:

Silane Steps In Preflush, In Plastic,

cc. cc.

1... Condition with Diesel oil and 1% 40 40 Hyflo.

2--- Preflush with .5% of silane in salt 15 water solution.

3.-- Space with 5% salt water solution. 10

.-- Introduce plastic 20 20 Overfiush with a 2.5% cresol in diesel 20 20 oil solution.

Compressive Strength (p.s.i.) Plastic N o silane Silane in Silane in Prefiush Plastic It is believed that these tests illustrate the superiority 5 of the sand consolidation method of the present invention over the prior art sand consolidation method.

EXAMPLE II A number of large scale tests were also made for com parison of permeabilities of various consolidations as well as compressive strengths thereof. The test chamber and other equipment used in these tests are described in a paper entitled, Large-Scale Laboratory Investigation of Sand Consolidation Techniques, by Wayne F. Hower and William Brown published in the December 1961 issue of Journal of Petroleum Technology.

Prcedure.350 pounds of wet Oklahoma #1 sand was packed in the test chamber. The sand packed chamber was placed in a water bath and heated to 130 F. before treatment. After treatment all outlets were plugged and the chamber was returned to the water bath and th plastic cured for 24 hours. Excess sand was removed by washing with water, and the consolidation was split The following treating sequences for each system were used.

Samples of the consolidations used for strength and permeability tests were taken from comparable areas.

Table I tabulates the results that were obtained in clean Oklahoma #1 sand using the gallon and gallon afterflush volumes. Tests A, B, and C should be compared with each other and likewise for tests C, D, and E.

TABLE I Test N o. A B C 4 D E F Amount silane in 1 gallon preflush Amount silane in 1 gallon plastic 5% salt water. Flow Rate-g p .8 Volume After flush Total Volume Consolidated cu. ft. Volume Harder Part-cu. ft 1.05 1. 475 1. 475 1. 2 l. 75 1. 75 Compressive strength in p.s.i.--

1 1, 650 2, 540 1, 350 850 2, 200 1, 840 2 1, 380 1, 000 350 265 1, 020 300 820 1, 060 1, 565 260 145 300 4 1, 790 1, 325 2, 490 550 300 650 5 97 900 1, 250 700 120 280 Permeability in millidarcies:

1 4,620 3,893 4, 280 4,301 4, 331 4, 004 2 3, 916 4, 131 5, 390 5, 597 6,326 5, 487 3,866 4, 350 4, 597 5, 111 6, 537 5, 818 4 5, 082 6, 355 4, 121 4, 774 4, 523 4, 041 5 5, 098 6, 752 5, 548 7, 144 5, 557 5, 646 Condition below perforation Good Good Good 1 Poor Set for 5 in. 2 Poor Set for 1% in.

in half. Samples were taken from various areas, with samples 1 and 2 being relatively close to the perforation and samples 3, 4 and 5 being somewhat further away. The above referred to paper by Hower and Brown il- Ta-ble II is a summary of our tests where the sand contained 2% bentonite. The sand was packed in brine and heated to 130 F. overnight and treated by the same procedure outlined hereinabove.

TABLE II Test No. G H J Amount silane in 1 gal. preflush 20. 4 cc Amount silane in 1 gal. plastio' 20. 4 cc 10. 2 cc. 5% salt water spacer 10 gal. Flow rate 1 7 g.p.m 1 88 g.p m 1. 7 g.p.m. Volume Afterflush 5 gal 5 5 gal. Total Volume Consolidated O 73 cu. ft 0.60 cu. ft. 0. 67 cu. ft. Volume Harder Part 0 58 on. it 0.46 cu. ft. 0. 60 cu. ft. Compressive Strength in p.s.i.

1, 742 1, 585 2, 579 2, 892 1, 712 1, 602 1, 721 2, 695 851 652 to 2,169 1,184 1,928 771 to 1, 887 2, 061 1, 303

Formalin cc 2750 M-P cresol cc 550 3,5 xylenol gms 67 Guanidine carbonate gms 510 36% caustic soda solution cc 127 Gamma-aminopropyltriethoxysilane (where EXAMPLE III A number of silanes were tested to determine their relative compatibility with the phenolic resin formula for 146 F. and their effect on the compressive strength of the set resin. The formula used was Formula B of Example II. The ingredients of this plastic formula plus 0.5 cc. of each of the various silanes were mixed in an eight ounce glass bottle and then placed in a 146 F. oil bath.

Compatibility of the silane in the plastic was noted when initially mixed therewith and before the plastic separated. The separation time was the time required for the plastic to separate from the excess water in the soluapplicable) cc 10.2 or 20.4 tion.

Oklahoma No. l sand was packed 2.5 inches deep in a 1 inch I.D. glass tube and treated as follows:

(1) Sand was saturated with brine.

(2) Conditioned with 40 cc. of diesel oil containing 1% oil soluble surfactant, Halliburton Hyfio.

(3) Treated with 20 cc. of plastic, which had been permitted to stand 9-10 minutes after mixing.

(4) Treated with 100 cc. of diesel oil containing 2.5% cresol.

(5) Stoppered the outlet of the glass tube and placed in a 146 F. oil bath for 24 hours.

All solutions were at 146 F. during treatment.

The following silanes or organosilicon materials were tested:

( 1) Gamma-aminopropyltriethoxysilane.

(2) N (beta aminoethyl) gamma aminopropyltrimethoxysilane.

(3) Delta-aminobutylmethyldiethoxysilane.

(4) N-methyl-gamma-aminoisobutyltriethoxysilane.

(5) N-methyl-gamma-aminopropyltriethoxysilane.

(6) Delta-aminobutyltriethoxysilane.

(7) N- (beta aminoethyl) gamma aminopropyltriethoxysilane.

(8) No silane added to plastic (control test).

(9) 3,4-epoxycyclohexylethyltrimethoxysilane.

( 10) Glycidoxypropyltrimethoxysilane.

(11) N,N, (diethyl) gamma aminopropyltriethoxysilane.

(12) Gamma-aminopropylsilicone.

Results Compatibility tests.Silanes 1, 3, 6, 10 and 11, were compatible in every way with the plastic.

Silanes 4, 5, and 9 formed a clear solution when first mixed but developed a slight haze in a short time. It is believed that these silanes can be successfully used in the Compressive Silane number: strength-psi. 1 1210 7 328 8 (control) 198 It can be seen that Silane No. 1 produced the best silane that was tested and that all silanes are better than the control. Silanes 2 and 7 are the chemicals that are not believed to be compatible in the plastic because of the rapid formation of a gummy reaction product. The plastic made using 2 and 7 penetrated the sand effectively but, where a large volume of plastic is forced through one perforation, it is believed that a severe permeability reduction of the sand near the perforation could develop.

Therefore, the use of these chemicals may not be desirable.

Although silanes of the general formulas disclosed in copending US. application Serial No. 260,826 filed February 25, 1963, may be used in the phenolic plastic employed in the present invention, superior results are obtained using a silane having the following general formulas:

wherein l) R =an alkyl group having from 3 to 10 carbon atoms with at least 3 carbon atoms being in a straight chain between the silicon and nitrogen atoms,

R and R =hydrogen, R or RqOH, with R being an alkyl group having from 1 to 5 carbon atoms, but both R and R cannot be R alone in the same compound,

R, and R =R or 0R where R, is an alkyl group having from 1 to 5 carbon atoms,

and (2):

R =an alkyl group having from 2 to 5 carbon atoms,

R =glycidoxy group or a cyclohexyl group having from 1 to 2 substituted epoxy groups,

R and R =R or OR where R is an alkyl group having from 1 to 5 carbon atoms,

Broadly the present invention relates to a new and improved method of permeably consolidating loose or incompetent sands employing a base catalyzed phenolic resin with a relatively small amount of a silane compatible therewith mixed therewith.

A number of field jobs have been performed using the method of the present invention. These jobs have shown a substantially higher degree of success than similar jobs performed using the prior art method described hereinabove.

What is claimed is:

1. A method of permeably consolidating loose sands, earthen formations or the like, consisting of the steps of:

(a) introducing a formation conditioner into the formation to be consolidated;

(b) introducing a phenolic resin containing a relatively small amount of gamma-aminopropyltriethoxysilane into the formation; and,

(c) introducing an oil overfiush solution containing a relatively small amount of cresol mixed therewith into the formation.

2. A method of permeably consolidating loose sands,

earthen formations or the like, consisting of the steps of:

(a) introducing a quantity of diesel oil containing from about .5 to about 3% of an oil soluble surface active agent into the formation to be consolidated;

(b) introducing a settable phenolic resin containing from about .05% to about 5% of a silane compatible therewith Selected from the group consisting of:

wherein (l):

R =an alkyl group having from 3 to 10 carbon atoms with at least 3 carbon atoms being in a straight chain between the silicon and nitrogen atoms,

R and R =hydrogen, R or R OH, with R; be-

ing an alkyl group having from 1 to 5 carbon atoms, but both R and R cannot be R alone in the same compound,

R and R =R or R where R is an alkyl group having from 1 to carbon atoms,

and (2):

R =an alkyl group having from 2 to 5 carbon atoms,

R =glycicloxy group or a cyclohexyl group having from 1 to 2 substituted epoxy groups,

R and R =R or OR where R is an alkyl group having from 1 to 5 carbon atoms,

R =OR into the formation; and,

(c) introducing an oil overflush solution containing from about 1% to about 3% cresol mixed therewith into the formation.

3. The method of claim 2, wherein said silane is gammaaminopropyltriethoxysilane.

4. A method of permeably consolidating loose sands,

earthen formations or the like, consisting of the steps of:

(a) introducing into the formation to be consolidated, a quantity of diesel oil containing a relatively small amount of an oil soluble surface active agent, thereby conditioning the formation;

(b) introducing into the formation a settable phenolic resin containing a relatively small amount of a silane selected from the group consisting of:

and

wherein (1):

R =an alkyl group having from 3 to carbon atoms with at least 3 carbon atoms being in a straight chain between the silicon and nitrogen atoms,

R and R hydrogen, R7 or RqQH, with R being an alkyl group having from 1 to 5 carbon atoms, but both R and R cannot be R alone in the same compound,

R and R =R or 0R where R is an alkyl group having from 1 to 5 carbon atoms,

and (2):

R =an alkyl group having from 2 to 5 carbon atoms,

R =g1ycidoxy group or a cyclohexyl group having from 1 to 2 substituted epoxy groups,

R and R =R or OR where R is an alkyl group having from 1 to 5 carbon atoms,

(c) introducing into the formation an oil overfiush solution containing a relatively small amount of cresol therewith, thereby consolidating the formation into a hard, permeable mass having a relatively high compressive strength.

References Cited by the Examiner UNITED STATES PATENTS 9/1962 Carlstrom et a1. 260-38 X OTHER REFERENCES Hower, W. F., Large-Scale Laboratory Investigation of Sand Consolidation Techniques, in Journal of Petroleum, 

1. A METHOD OF PERMEABLY CONSOLIDATING LOOSE SANDS, EARTHEN FORMATIONS OR THE LIKE, CONSISTING OF THE STEPS OF: (A) INTRODUCING A FORMATION CONDITIONER INTO THE FORMATION TO BE CONSOLIDATED; (B) INTRODUCING A PHENOLIC RESIN CONTAINING A RELATIVELY SMALL AMOUNT OF GAMMA-AMINOPROPYLTRIETHOXYSILANE INTO THE FORMATION; AND (C) INTRODUCING AN OIL OVERFLUSH SOLUTION CONTAINING A RELATIVELY SMALL AMOUNT OF CRESOL MIXED THEREWITH INTO THE FORMATION. 